Split engine



2 Sheets-Sheet l INVENTOR.

a BY Q) v I ATWPMY S. H. MICK SPLIT ENGINE Jan. 5, 1960 Filed Oct. '10, 1958 s. H. MICK SPLIT ENGINE Jan. 5, 160

2 Sheets-Sheet 2 Filed Oct. 10, 1958 FUN INVENTOR. BY jgQ/243 /37%/k? ATraP/YQ United States Patent SPLIT ENGINE Stanley H. Mick, St. Clair Shores, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application October 10, 1958, Serial No. 766,616

'5 Claims. (Cl. 123-127) The present invention relates to an engine control system in which it is possible to operate the engine on less than all of the cylinders under normal or light load conditions but in which full engine operation is possible when the engine load exceeds a given value. The present invention is an improvement over copending application Serial No. 608,828, Dolza, filed September 10, 1956, now Patent No. 2,875,742, granted March 3, 1959.

As explained in the aforenoted copending application, it has been found that considerable economies can be realized when it is possible to resort to split engine operation, for example, being able to operate an eight cylinder engine on four cylinders under moderate load conditions.

The economy is effected by the fact that individual cylin der efficiency is increased when the individual cylinder load is increased during split engine operation in contrast to reduced cylinder loads as occurs with full engine operation during light or moderate load conditions.

It is an inherent characteristic of an internal combus-' tion engine to be most efficient under high load conditions. This is attributable to the quantity of air fed to the cylinders. Maximum air is supplied to the cylinders when the throttle is open, indicative of high load, therefore, more air may be compressed in turn increasing the compression ratio. Since engine efficiency increases with compression pressure and compression pressure increases with cylinder load, the desirability of split or part cylinder engine operation as a means for main taining high cylinder loads becomes apparent.

Split engine operation has long been recognized as a theoretically desirable goal. plication of mechanism which have been developed to achieve this type of operation have thus far precluded its commercial feasibility. The present invention relates to a greatly simplified split engine control system-which has been operated over a considerable period of time and has proved to be most satisfactory in operation.

The invention is illustratedwith an eight cylinder although it is apparent that it may be applied to engines having any number of cylinders in excess of one; Separate air intake passages, throttles and manifolds are ro-.

vided for the active and inactive'cylinders;

. ,Itis apparent that alternate firing cylinders should be selected for active or inactive cylinders. In other words, a normal firing order for an eight cylinder engine might be 1-8-4-3-6-5-7-2. The active cylinder group might then be cylinders 1-4-6-7. v I 3 In general, the operation of the split-engine control system is such that when the manifold vacuum is abovea given value, e.g., 4 inches of mercury or greater, in the manifold serving the four active cylinders, the engine is operated on these four cylinders only and controlled by an active throttle device which regulates flow through one of the two air intake passages. When part or four cylinder operation is effected, an inactive throttlein the other air induction passage is moved to a full open position to prevent pumping losses in the inactive cyli'n':

However, the general com-- ders. -At the same time fuel flow to the inactive nozzles is also cut off;

contemporaneously with the opening of the inactive throttle and the cutting oif of fuel flow to the inactive nozzles, means is provided for shifting an accelerator pedal controlled throttle linkage to a position increasing the opening of the active throttle beyond the amount which would otherwise exist during eight cylinder engine operation. This latter adjustment of the active throttle durtion when eight cylinder operation is in effect necessary in order to provide a smooth transition between four and eight cylinder engine operation. The latter is necessary in order to make the transition at substantially constant engine torque.

' load or high power demand conditions.

is provided which maintains the metering linkage in an economy position when manifold vacuum is above a pre determined value indicative of normal load. Spring means is adapted to shift the linkage to the maximum powerposition when manifold vacuum falls offdue to heavy loads or power demands.

This type of operation is generally the same as shown and described in copending application Serial No. 591,889, Dolza, filed June 18, 1956.

However, in adapting the Dolza' type system to split L engine operation, difficulty is experienced in the aforenoted engine load control of the metering linkage. It is not economical to use split engine, e.g. four cylinder, operation at fuel-air mixtures richer than the economy ratio. During split engine operation the degree of active I throttle opening is increased to insure a smooth transition from full to part cylinder operation. This added throttle opening may result in a drop in manifold vacuum to onefourththe full engine vacuum. This vacuum drop would normally be enough to cause the power servo toshift the metering linkage to the maximum power position in response to what is actually a false demand for fuelen richrnent. I

The present invention is directed to an improved power servo device which is responsive to full and split engine operation so as to maintain the metering linkage in its economy position during split engine operation. The details, as well as other objects and advantages, of the present invention will be apparent from a perusal of the'detailed description which follows.

{In the drawings: Figure 1 is a diagrammatic representation of a system embodying the subject invention; and "Figures 1a, 1b and 1c are enlargements of Figure 1. Y

Re ferring to the drawings, a manifold is indicated generally at 10 and is of the divided header type in which individual air induction passages 12 and 14 are adapted respectively to supply air to four of the engine cylinders? through individual cylinder intake passages 16 and 18.-

fuel

portions. of

"' Throttle valves 20 and 22 are disposed in each of the F are disposed-in the individual cylinder intake passages are adapted to supply fuel to cylinders 30 when the cylinder intake valves 32 are open.

In the present control system, as in the aforenoted copending application, a group of cylinders and associated air intakes are always active whereas the remaining cylinders are normally inactive with the latter beingactivated only after the engine load exceeds a given value. In the present illustration, intake 12, throttle 20 and the four associated cylinder intake passages 16 are the active part of the system whereas intake 14, throttle 22 and intake passages 18 constitute the normally inactive part of the system.

Fuel is adapted to be supplied to the nozzles 28-29 through a fuel injection metering device indicated generally at 34 which is shown and described in detail in copending application Serial No. 608,853, Dolza, filed September 10, 1956, now Patent No. 2,843,098, granted July 15, 1958. Except as hereinafter pointed out the fuel metering system functions in the same manner as described in the aforenotcd copending application Serial No. 608,853.

Air is drawn in through both induction passages as already noted. However, only the active induction passage 12 includes a piezometer ring 36 which transmits a vacuum signal proportional to mass air flow through conduit 38 to a metering control diaphragm 40 of the fuel control mechanism 34. Inasmuch as two intake induction passages are utilized in the subject split engine, it is possible for venturi 25 to be reduced sufiiciently in size such that one-half engine operation will produce the same metering signal in piezometer ring 36 as total engine air flow would produce on the single venturi used in the aforenoted Dolza application Serial No. 608,853. Further, since venturi depression in piezometer ring 36 is proportional to the nozzle pressure drop across all of the nozzles 23 and with equal air flow restriction in each induction passage, due to coordinated (equal opening) positioning of the throttles, the venturi signal may be taken off from the active induction passage during all operating conditions.

Fuel control mechanism 34 is adapted to supply fuel pressure to conduit 42 in proportion to mass air flow. A branch conduit 44 is supplied from conduit 42. Conduits 42 and 44 respectively lead to distributors46 and 48 which in turn supply the active and inactive nozzles through individual conduits 50 and 52.

As described in the copending Dolza applications, diaphragm 40, through a rod 39 centrally fixed thereto, is articulated to a lever 41 at 43. Lever 41 is also articulated at 43 to counter-balancing lever 45 and the latter pivotally mounted on a fixed pivot 47. End 49 of lever 41 engages a fuel metering bypass valve 51. Under the influence of venturi vacuum from conduit 38, diaphragm 40 is adapted to rotate lever 41 about an adjustable fulcrum lever 53 mounted on a fixed pivot 55.

A control rod 57 is articulated to lever 53 and is adapted, through power servo 59, to move the lever between power and economy stops 61 and 63. As movable under, pressure to raise the sleeve uncovering bypassports 67 and decreasing the fuel supplied to conduit 42.

Throttles 20 and 22 are interconnected through a linkage mechanism indicated generally at 54 for synchrom'zed operation by the operator throughthe'actuation of an accelerator pedal 56. Accelerator controlled linkage 64. The lower end of member '72 is pivotally mounted on a fixed support 74.

The pivotal connection 70 between lever portions 66 and 70 has a link 76 articulated thereto and the other end of which link is connected to a rod 78 of a servo device indicated generally at 80. Servo device 80 includes a pair of casing members 82 and 84 which peripherally clamp a flexible diaphragm 86 therebetween. Rod 78 is'centrally fixed to the diaphragm and extends through an opening 33 in casing 84. A spring 89 is disposed in servo chamber 90 and tends to bias diaphragm.

86 to the right. It is possible, however, to eliminate spring 89. if desired.

Theupper end of lever 64 has a spring 92 connected thereto, the other end of which is grounded at 94. Assuming for the moment that all other control forces remain unchanged, it is apparent that as the accelerator pedal 56 isdepressed the throttle linkage system is such that the active throttle 20 will be opened. It should be noted at this point that the pivoted connection 70 between members 66 and 72 of double articulated lever 64 may be pivoted between two positions by servo mechanism 80 in conjunction with spring 89. during eight cylinder operation, the vacuum forces on either side of diaphragm 86 are substantially balanced, spring 89, through rod 78 and link '76, will shift pivoted connection point 70 in a rightward direction as shown in the drawing. This action causes a counterclockwise rotation of member 66 moving throttle 20 in a closing direction. As will be subsequently considered in greater detail when the vacuum in chamber 96 overcomes spring 89 the parts will be shifted to the dotted line positions to open throttle 20. As will subsequently be more apparent, this dilferential movement of the active throttle 20 is for the purpose of readjusting the throttle position to faciliate a smooth transition between four and eight cylinder operation.

During this eight or full cylinder operation, actuation of accelerator pedal 56 will cause the double articulatedlever 64 to pivotabout support 74. As will subsequently be considered in greater detail, however, during four or part cylinder operation, lever portion 66 will pivot about point 70 thus providing differential control of throttle actuation.

Active throttle lever 58 is articulated through a link 96 to an arm 98 loosely mounted on the inactive throttle valve shaft 100 so that the actuation of the active throttle may or may not affect a similar movement of the inactive throttle 22 depending on the actuation of other devices which will be subsequently considered. A lever 102 is fixed to the inactive throttle shaft 100 and includes a tab portion 104 adapted to engage with the loosely mounted lever 98. Assuming the system control forces are such that the inactive throttle 22 is in a closed position, as shown, then the levers 98 and 102 are in operativeengagement and opening movement of the active throttle 20 will likewise open the inactive throttle.

The various devices utilized to vary the subjectfuel system between split and full operation will now be considered. In general, it has been found that as longfas the manifold vacuum in the activeportion 106 of manifold 10 is above a predetermined value, e.g., four inches of mercury, most economical engine operation will be achieved by split or four cylinder operation of the engine with the remaining cylinders being inactivated.

When, as is the case in'thecasing 112 and is connected to link 122 articulated to lever 102. A spring 124 disposed in chamber 125 between diaphragm 116 and casing 114 normally urges' the lever 102 and throttle 22 in a counterclockwise or closing direction and under which condition, as noted, tab 104 of lever 102 is in engagement with active throttle controlled lever 98.

The actuation of servo 110' is under the control of a shift valve device indicated generally at 126. Device 126 includes a plurality of casing members 128, 130 and 132. Casing 132 includes a ported cylindrical opening within which a spool type valve member 134 is slidably disposed. Valve member 134 includes astem 136 extending toward casings 128 and 130 and upon which a pairv of flexible diaphragms 138 and 140 are centrally mounted. The first diaphragm 138 is peripherally clamped between casings- 128 and 130 while the second and smaller diaphragm 140 isperipherally clamped by the casings 130 and 132.

Chamber 142 defined by casing 128 and diaphragm138 is connected through a passage 144 with the active manifold 1 06 whereby active manifold vacuum is at all times transmitted to the chamber.

Chamber 146 defined by diaphragms 138 and 140 and casing 130 is communicated through a conduit 148 with the inactive manifold 150 and likewise is at all times subject to the vacuum force extant therein. A spring 152 is also disposed in vacuum chamber 142 and biases spindle'valve 134 in a rightward direction which, other control; forces permitting, causes conduit 154 communicating with chamber 125 of servo 110 to be exhausted to the atmosphere through an exhaust port 158 in casing 132. In such case spring 124 would move inactive throttle -22 in'a throttle closing direction.

So long as the vacuum in manifold 106 exceeds that in manifold 150 by a differential of four inches of mercury, the vacuum force in chamber 142 will be suificiently strong to overcome spring 152 as well as the vacuum force in chamber 146 to shift valve 134 to the left. Under this circumstance active manifold vacuum from conduit 160 will be admitted from valve casing port 162 between the lands of valve 134 where it will act through conduit 154 on inactive throttle diaphragm 116 to shift the diaphragm to the right against the force of spring124 to fully open the inactive throttle.

At the same time, the vacuum forces from manifolds 106 and 150 are respectively transmitted through conduits 164 and 166 to chambers 90 and 91 of accelerator control linkage servo 80. The same vacuum differential will cause diaphragm 86 of servo 80 to be shifted to the left moving the pivotal connection 70 to its leftmost position in which a stop 168 on member 72 of lever 64 abuts a fixed stop 170. The leftward movement of pivotal connection 70 causes member 66 of lever 64 to be rotated in a clockwise direction increasing the opening of the active throttle in order to maintain a constant engine torque for smooth transition to four cylinder operation, supra. As noted, supra, lever 66 now pivots about point 70 providing differential control whereby the active throttle 20 will open to a greater extent than during corresponding eight cylinder operation.

contemporaneously with the shifting of the throttle linkage and the opening of the inactive throttle, a servo valve device 172 is adapted to cut off the flow of fuel to the inactive nozzle distributor 48. Servo valve device 172 includes a pair of casing members 174 and 176 peripherally clamping a diaphragm 178 therebetween and thereby forming a pair of vacuum chambers 180 and 182.

Vacuum chambers 189 and 182 in turn communicate through conduits 184 and 186 with active and inactive manifold vacuum conduits 144 and 148. A control rod 188 is centrally fixed to diaphragm 178 and terminates in a' valve portion 190 which, when the predetermined vac-- l The transition from split or four cylinder operation to eight or full engine operation is, as noted, affected when the vacuum in the manifold 106 drops below a predetermined value, e.g., four inches of mercury. When this happens the force of spring 152 acting on the shift valve 1 device diaphragm 138 will cause valve 134 to be moved to the right atmospherically venting inactive throttle servo chamber and causing'the spring 124 to move the inactive throttle towards a closed position and operatively engaging inactive throttle levers 102 and 98 whereby sy'nchronized operation of the throttles will thereafter take place. 1

Closing the inactive throttle substantially equalizes the vacuum in manifolds 106 and 150 under which conditions the vacuum forces on either side of linkage controlling servo diaphragm 86 will be substantially equal and spring 89 will shift the active throttle 20 to a more closed position, supra. Again, the equal vacuum in mani folds 106 and 150 will be transmitted to fuel cut-off valve servo chambers 180. and 182'permitting spring 192 to open valve 190 and thereby initiating fuel flow to inactive nozzles 29.

During eight or full cylinder operation the active and inactive manifold vacuums are equal resulting in no vacuum force diiferential acting on shift valve diaphragm 138 However, whenthe vacuum'in chamber 146 of the shift valve device 126 exceeds a given value, e.g., 15 inches of mercury, it will act on the small diaphragm with sufficient force to overcome spring 152 and shift the valve 134 to the left. This again fully opens the inactive throttle which once again causes the servos 80 and 172 to again adjust the throttle Valves and fuel flow to four cylinder operation.

Power servo 59 includes casing members 200 and 20-2 peripherally clamped between which is a first diaphragm 204. Diaphragm 204 is centrally fixed to an extension 206 of rod 57. A second diaphragm 208 is mounted on casing 200 and is likewise centrally fixed to rod extension 206.

Diaphragm 204 and casing 202 define a chamber 210 communicated through conduits 212 and 144 with active manifold 106. Diaphragms 204 and 208 with casing 200 define a chamber 214 communicated through conduits 216 and 148 with inactive manifold 150.

A chamber 218 defined by diaphragm 208 and casing 200 is open to atmosphere.

As already noted, it is desired to maintain the metering control linkage in its economy position, i.e. fulcrum 53 against stop 63, during split engine operation. To this end diaphragm 204 is larger than diaphragm 208 in the same ratio as the vacuum drop in the active manifold' between full and split engine operation. To illustrate, if the vacuum drop is in the ratio of 4:1 then diaphragm 204 should be four times as large as diaphragm 208.

The operation of power servo 59 is as follows: during full engine operation, the manifold vacuum in manifolds 106 and and, therefore, in servo chambers 210 and 214 are equal. The vacuum forces acting on diaphragm 204 are, therefore, balanced and the vacuum force acting on diaphragm 208 must balance against the force of spring 220. When the vacuum force is above a predetermined value, e.g. 6-8 inches Hg, its action on diaphragm 208 will overcome the force of spring 220 to move fulcrum lever 53 against economy stop 63. During split engine operation, inactive throttle 22 is fully open, therefore, the vacuum in servo chamber 214 is substan;

7 tially zero and the vacuum in chamber 210 perhaps one fourth the value during full engine operation. However, since diaphragm 2&4 is larger in area. e.g. four times, than diaphragm 208 fulcrum lever 53 is still maintained in its economy position.

It is apparent that the vacuum drop in the active manifold 106 between full and split engine operation and the area differential between diaphragms 294 and 208 are merely illustrative and may in actual practice vary from the ratios noted.

It is apparent that the subject invention has been diagrammatically represented in order to simplify the understanding of its operation. it is also apparent that the substance of the subject invention may be embodied in various structural arrangements Within the intended scope of the hereinafter appended claims.

I claim:

l. A charge forming device for an internal combustion engine comprisin a first air induction system for supplying air to certain cylinders of the engine, a second air induction system for supplying air to the remaining engine cylinders, first and second throttle valves for respectively controlling the flow of air through said first and second systems, means for supplying fuel to each of said air induction systems in accordance with engine demand, means for synchronizing the actuation of said throttles, means responsive to the engine vacuum differential in said air induction systems posteriorly of said throttles for fully opening one of said throttles when said differential exceeds a predetermined value, additional means responsive to said predetermined vacuum differential for moving the other throttie to a more open position when said one throttle is fully opened, means operable in response to said predetermined vacuum differential to cut off the flow of fuel to the air induction system associated with the fully opened throttle, said fuel supplying means including a servo device for varying the fuel-air ratio in response to variations in engine load, and means rendering said servo device non-responsive to pressure differentials between said induction systems occasioned solely by rendering one of said systems inoperative.

2. A charge forming device for an internal combustion engine comprising a first air intake passage, a first manifold communicating with said intake passage and a first group of individual cylinder mixture passages leading from said manifold to certain of the cylinders of the engine, a second air induction passage, a second manifold communicating with said second induction passage, a second group of individual cylinder mixture passages communicating with said second manifold and leading to the remainder of the engine cylinders, venturi means in each of said air intake passages, throttle valves for respectively cotrolling the flow of air through said intake passages, 21 fuel nozzle disposed in each of said individual cylinder mixture passages, fuel metering means for supplying fuel to said nozzles in accordance with the mass of air flow through the venturi means of one of said intake passages, linkage means interconnecting said throttle valves and adapted to synchronize operation of said valves, accelerator pedal control means adapted to actuate said linkage means, means responsive to the vcuum differential between said manifolds and adapted when said differential exceeds a predetermined value for fully opening the-throttle valve 7 associated with the lower vacuum manifold, a servo mechanism responsive to said predetermined vacuum differential to move the throttle valve associated with the higher vacuum manifold toward a more open position, another servo operable in response to said vacuum differential to cut off the how of fuel to those nozzles associated with the lower vacuum manifold, said fuel metering means including a fuel metering valve, a firstdiaphragm operable in accordance with said mass of air flow, linkage means connecting said diaphragm and said metering valve, a servo device adapted to modify the actuation of the linkage means to vary the fuel-air ratio in response to variations in engine load, and means rendering said servo device non-responsive to pressure differentials between said induction systems occasioned solely by rendering one of said systems inoperative.

3. A charge forming device as set forth in claim 2-in which said servo device comprises a control rod operatively connected to the linkage means, spring means normally biasing said rod to increase the fuel-air ratio, firstand second casing members, a first diaphragm peripherally.

clamped between said casing members and defining first and second chambers respectively therewith, a second diaphragm mounted within one of said casing members and communicating with said first chamber, said first and second diaphragms being connected to said control rod, a conduit communicating said second chamber with one of said manifolds, a conduit communicating the first chamber with the other of said manifolds, said second diaphragm being adapted to maintain said linkage means in a relatively low fuel-air ratio position when the vacuum in said manifolds is equal and above a predetermined value to overcome the force of said spring, said first diaphragm being adapted to maintain linkage means in said low fuel-air ratio position when there is a vacuum differential between said chambers and the larger vacuum force exceeds the force of said spring.

4. A charge forming device as set forth in claim 3 in which the movement of the throttle valve associated with the higher vacuum manifold toward said open position will cause a predetermined vacuum drop in said manifold, said first diaphragm being larger than said second diaphragm to compensate for said predetermined vacuum drop whereby said linkage means is maintained in said low fuel-air ratio position.

5. A charge forming device as set forth in claim 1 in which the movement of said other throttle to a more open position causes a predetermined vacuum drop in the associated manifold, and further in which the means rendering said servo device noirresponsive to said pressure differentials includes a pair of diaphragms having an area differential therebetween adapted to offset the effect of said predetermined vacuum drop on said device.

No references cited. 

